Three-fold leveling

By Nick Wright

Lee Steel produces super flat steel with its new multi-blanking line to secure business

September 2012 - In the last few months, steel service center Lee Steel Corp., Novi, Mich., has kept writers busy as it’s made industry headlines. The company recently modernized the interior of its corporate headquarters. This summer, it broke ground on a new plant near Detroit. But across the state in Wyoming, a Grand Rapids suburb, the company boosted its flat-rolled carbon services. For the material that represents Lee Steel’s bread and butter, it’s now running a state-of-the-art, precision multi-blanking line with three different leveling systems that all but guarantee its steel is impeccably flat.

Red Bud Industries, Red Bud, Ill., supplied the main coil processing line for which Lee Steel constructed a 40,000-square-foot addition to its facility last fall. At the heart of the line’s flattening capabilities are three key integrated systems: Red Bud’s stretcher-leveler and a dual cassette leveler with an AutoFlat leveling system from machinery manufacturer Machine Concepts, Minster, Ohio.

It’s the first line installed in the Grand Rapids area in approximately the last 15 years, says Tom Taylor, vice president at Lee Steel. There are toll processors with blanking lines, but Lee wanted an established service center-based multi-blanking line for quick turnarounds on a mix of steel types, grades and gauges. This gives the company a competitive edge.

“Having the multi-blanking line in-house allows us to run as little or as much as the customer requires,” Taylor says. “Additionally, the line was set up to run exposed material, so there is no worrying about an outside processor putting any defects into our Class 1 material.”

The markets for Lee Steel’s flat products include automotive, furniture and agricultural. Although Lee Steel processes mainly carbon steel, it can run other materials such as aluminum, stainless, galvanized and prepainted. Some of its material goes into appliances, as well.

“It has to have a higher quality. It can’t have any surface defects so the line is set to run Class 1. It’s pretty much perfect material—super flat with a super clean surface,” Taylor says.

Flattening on the fly

When Lee Steel ordered the 0.135-inch- by- 72-inch line, Red Bud recommended Machine Concepts’ dual cartridge leveler for its robustness and quality, according to Taylor. As the first of several flattening steps in the line, the dual-cassette aspect of Machine Concepts’ G3DC leveler lets the shape correction leveler cover a broader gauge range.

With a push-button-controlled exchange table, operators can swap large-diameter work rolls for smaller work rolls on the fly to process lighter-gauge materials, says Guil Bergman, product manager at Machine Concepts.

“As the gauge goes up, the thickness goes up and you need larger-diameter work rolls,” he says. “So this increases the gauge range of the leveler by exchanging small rolls with big rolls and vice versa.”

The dual cassette has a series of work rolls on the top and bottom through which the strip S-wraps. “The penetration is deep on the entry end to put a large percentage of material thickness beyond the yield point,” Bergman says. “That penetration feathers out so you can flatten material. But the machine also has roll bending capability, which allows you to vary penetration in zones from edge to edge.”

Lee Steel also added Machine Concepts’ proprietary AutoFlat system. This second feature supplements the dual cassette leveler. AutoFlat is another device, essentially a sensing system, that reads the strip shape as it exits the leveler. It then seeks proper flight positions to create and maintain flatness dynamically, even if material shape changes during the course of the coil.

“It basically closes the loop and automates the leveling process,” Bergman adds. Setting the roll bending, which is done by adjusting backup flights, is “quite an art; it takes a good operator who knows what he’s doing.”

Machine Concepts’ split drive system, a key feature of its leveler, has four drive inputs: two on top and two on the bottom. With this system, the exit roll cluster runs slightly faster than the entry rolls to compensate for differential roll speeds. The system also adds tension to the strip between the roll clusters. This improves the leveling process, reduces slippage in the roll cluster, and minimizes internal torque windup, Bergman says.

Lee Steel benefits beyond improved leveling from Machine Concepts’ split-drive system. Because of the top-and-bottom multi-roll configuration, operators can open the cassette and insert a cleaning pad, which sits in between the rolls. This roll-clean feature drives the upper rolls and lower rolls in opposite directions, lodging the pad as the rolls spin against it.

“The roll rotation is then reversed so it scrubs back and forth,” Bergman says. “It’s pretty effective in keeping rolls clean, and the operator can clean the rolls every coil, if he desires, fairly easy just while he’s threading the next coil.”

Opening doors

Lee Steel has leveraged its 70,000-pound coil capacity line to access new customers and better serve existing ones. “The line definitely opened up a lot of doors for us to break into new markets that we wouldn’t have ordinarily served just having slitters before,” Taylor says. Because the service center doesn’t need to send coils to outside processors, Lee Steel can offer shorter lead times on blanks.

When material exits Machine Concepts leveler, it’s very flat. The Red Bud stretcher-leveler further takes the memory and stress out of the steel blanks. By gripping and pulling the memory from the steel under incredible tension, Lee Steel prevents spring-back during stamping or laser cutting, retaining the panel-flat profile, says Taylor.

The combination of innovations from Machine Concepts and Red Bud lets Lee Steel produce blanks within a 0.005-inch tolerance. Red Bud, which acted as a liaison between Machine Concepts and Lee Steel, provided several features in the line for which it’s well-known among service centers. This includes Red Bud’s precision grip feed system, CNC programmable slitter and automatic strip divider. An automatic part diverter, part sorter and automatic lowering stack table make material handling easy. For Lee Steel’s appliance customers, the line is equipped with an applicator that puts a thin plastic film on stainless steel, which consumers peel off.

The line also features a computerized measuring table, which measures length, width, squareness and flatness in a simple digital operation, says Taylor. “This allows us to ensure that our material meets or exceeds our customers’ demanding specifications, every time.”

Smooth steel simplified

Putting up a new building always has its challenges, says Taylor. But given the complexity and size of the line, installation and launch were fairly routine. Plus, because Lee Steel’s operators were familiar with its existing slitting line, it cross-trained its crew to run the new line. “We show them how to set it up, utilize it, what to watch out for and make recommendations,” says Bergman. Machine Concepts typically take a hands-on approach where its representatives train the group of operators directly and run them through the processes.

“Luckily the winter was mild this year so it went relatively smooth,” Taylor says, noting the Wyoming plant is running one shift six days a week plus overtime when necessary. “As we build business on that line we’ll add a second shift onto it,” he says.

Machine Concepts, Red Bud and Lee Steel worked together to equip the line with its own router and dedicated IP address, “so if there’s any issues they can diagnose remotely,” Taylor says. Although this line is the first time Machine Concepts and Lee Steel have worked together, the latter is currently developing a wet-leveler system for Lee Steel’s new Red Bud EPS pickling line to be installed at its new plant in Romulus, outside Detroit.

For materials coming off the multi-blanking line, Lee Steel is hearing positive feedback.

“So far, everyone we’ve shipped steel to loves the flatness of it,” Taylor says. “And the tolerance on the length, width and diagonal is tighter than industry standards, so they’re loving the tolerances coming off the line. The surface of the steel and the flatness is remarkable.” MM